#define _CRT_SECURE_NO_WARNINGS 1
/**
*      author: Y_Yao
*      created: 2025-02-21 10:14:12
**/

#include<bits/stdc++.h>

#define int LL
using namespace std;
using LL = long long;
const LL LLINF = 1e18;
const int INF = 0x3f3f3f3f;
const int N = 1e5 + 7;
int a[N];
int n;

void solve()
{
    cin >> n;
    unordered_map<int, int> mp;
    for (int i = 1;i <= n;i++)
    {
        cin >> a[i];
        mp[a[i]]++;
    }

    int ans = 0;
    for (auto& e : mp)
    {
        if (e.second < e.first)
        {
            ans += e.second;
        }
        else if (e.second > e.first)
        {
            ans += e.second - e.first;
        }
    }

    cout << ans << endl;
}

signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);

    int t = 1;
    //cin >> t;
    while (t--)
    {
        solve();
    }
    return 0;
}